Exploring Inorganic Flexible Electronics: III‐Nitride Light‐Emitting Diode Epilayers on Wafer‐Scale Exfoliable Mica Substrate

Mica is a promising substrate for flexible photonic applications because it can be fabricated using wafer‐scale multiple exfoliations. However, the large lattice mismatch between mica and III‐nitrides hinders their application in III‐nitride semiconductor devices. In this study, two types of light‐emitting diode (LED) epilayers, blue and green, are epitaxially fabricated on 2‐inch exfoliated mica substrates using sputtered AlN as a buffer layer to address the lattice mismatch. The LED epilayers on mica substrate exhibit excellent single‐crystalline quality with a low threading dislocation density of 2.07 × 10 9 cm −2 in the GaN region and smooth surface morphology with a root mean square (RMS) roughness of 0.58 nm in a 5 × 5 µm 2 scanned area, demonstrating that mica is an excellent platform for III‐nitride semiconductors. Moreover, the structures are reproduced stably on multiple exfoliated mica at the wafer scale, which verified the reusability and reproducibility of III‐nitride/mica in terms of crystallinity, surface morphology, and transparency. Strong electroluminescence of the LED epilayers confirmed the potential of mica in electrically driven flexible opto‐electronics. Therefore, this results demonstrated the potential of mica substrates in III‐nitride semiconductors and provide a novel pathway for revolutionizing the fabrication of III‐nitride‐based flexible devices.